The Oregon Wheat Commission has maintained since the rogue strain was discovered that it was limited to one field. Federal investigators said they've found no other cases.

According to translated remarks the commission provided from Japan's minister of agriculture, Japan will begin to accept U.S. Western wheat again on Aug. 1 and soft white on Aug. 7.

The USDA on Tuesday confirmed Japan's resumption of wheat imports. Japan will test U.S. imports for genetically modified wheat for an undisclosed period of time.

U.S. Sen. Ron Wyden said in a press release on Tuesday that the announcement gives assurances to customers of Northwest wheat.

"This announcement means that all of Oregon's Asian customers are now confident that the wheat they are buying is free of genetically modified organisms," Wyden said.

The announcement comes in the middle of the harvest for Northwest soft white wheat growers in Oregon, Washington and Idaho.

"I think we were optimistic that they were working their way to this decision," Rowe said. "We didn't think it would happen quite this quickly, but we're thankful that it did."

Agriculture Department officials have said the modified wheat discovered in the Oregon field is the same strain as a genetically modified wheat that was designed to be herbicide-resistant and was legally tested by seed giant Monsanto a decade ago but never approved.

The modified wheat was discovered when field workers at an Eastern Oregon farm were clearing acres for the bare offseason when they came across a patch of wheat that didn't belong. The workers sprayed it, but the wheat wouldn't die, so the farmer sent a sample to Oregon State University to test.

A few weeks later, Oregon State wheat scientists discovered that the wheat was genetically modified. They contacted the USDA, which ran more tests and confirmed the discovery.

Most of the corn and soybeans grown in the United States are already modified, or genetically altered to include certain traits, often resistance to herbicides or pesticides. But the country's wheat crop is not, as many wheat farmers have shown reluctance to use genetically engineered seeds since their product is usually consumed directly. Much of the corn and soybean crop is used as feed.

The USDA has said the wheat would be safe to eat if consumed. But American consumers, like many consumers in Europe and Asia, have shown an increasing interest in avoiding genetically modified foods.

There has been little evidence to show that foods grown from engineered seeds are less safe than their conventional counterparts, but several state legislatures are considering bills that would require them to be labeled so consumers know what they are eating.